From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756543AbcBHVsl (ORCPT ); Mon, 8 Feb 2016 16:48:41 -0500 Received: from mailapp01.imgtec.com ([195.59.15.196]:38801 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755351AbcBHVsk (ORCPT ); Mon, 8 Feb 2016 16:48:40 -0500 Subject: Re: [PATCH] MIPS: Always page align TASK_SIZE To: Joshua Kinard , David Daney References: <1454954723-24887-1-git-send-email-harvey.hunt@imgtec.com> <56B8DA56.9020108@caviumnetworks.com> <56B8DB2D.3070604@imgtec.com> <56B90A3E.7000507@gentoo.org> CC: , , David Daney , Paul Burton , James Hogan , From: Harvey Hunt Message-ID: <56B90D30.5020904@imgtec.com> Date: Mon, 8 Feb 2016 13:48:32 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <56B90A3E.7000507@gentoo.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.20.79.140] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Joshua, On 02/08/2016 01:35 PM, Joshua Kinard wrote: > On 02/08/2016 13:15, Harvey Hunt wrote: >> Hi David, >> >> On 02/08/2016 10:11 AM, David Daney wrote: >>> On 02/08/2016 10:05 AM, Harvey Hunt wrote: >>>> STACK_TOP_MAX is aligned on a 32k boundary. When __bprm_mm_init() >>>> creates an >>>> initial stack for a process, it does so using STACK_TOP_MAX as the end >>>> of the >>>> vma. A process's arguments and environment information are placed on >>>> the stack >>>> and then the stack is relocated and aligned on a page boundary. When >>>> using a 32 >>>> bit kernel with 64k pages, the relocated stack has the process's args >>>> erroneously stored in the middle of the stack. This means that processes >>>> receive no arguments or environment variables, preventing them from >>>> running >>>> correctly. >>>> >>>> Fix this by aligning TASK_SIZE on a page boundary. >>>> >>>> Signed-off-by: Harvey Hunt >>>> Cc: David Daney >>>> Cc: Paul Burton >>>> Cc: James Hogan >>>> Cc: linux-kernel@vger.kernel.org >>>> --- >>>> arch/mips/include/asm/processor.h | 6 +++--- >>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/arch/mips/include/asm/processor.h >>>> b/arch/mips/include/asm/processor.h >>>> index 3f832c3..b618b40 100644 >>>> --- a/arch/mips/include/asm/processor.h >>>> +++ b/arch/mips/include/asm/processor.h >>>> @@ -39,13 +39,13 @@ extern unsigned int vced_count, vcei_count; >>>> #ifdef CONFIG_32BIT >>>> #ifdef CONFIG_KVM_GUEST >>>> /* User space process size is limited to 1GB in KVM Guest Mode */ >>>> -#define TASK_SIZE 0x3fff8000UL >>>> +#define TASK_SIZE (0x40000000UL - PAGE_SIZE) >>>> #else >>>> /* >>>> * User space process size: 2GB. This is hardcoded into a few places, >>>> * so don't change it unless you know what you are doing. >>>> */ >>>> -#define TASK_SIZE 0x7fff8000UL >>>> +#define TASK_SIZE (0x7fff8000UL & PAGE_SIZE) >>> >>> Can you check your math here. This doesn't seem correct. >> >> Thanks for spotting that - it should have been: >> >> (0x7fff8000UL & PAGE_MASK) >> >> I'll do a v2 now. >> > > FYI, TASK_SIZE was recently changed to 0x80000000UL in commit 7f8ca9cb1ed3 on > the linux-mips.org tree. Thanks, I'll rebase. > > >>> >>>> #endif >>>> >>>> #define STACK_TOP_MAX TASK_SIZE >>>> @@ -62,7 +62,7 @@ extern unsigned int vced_count, vcei_count; >>>> * support 16TB; the architectural reserve for future expansion is >>>> * 8192EB ... >>>> */ >>>> -#define TASK_SIZE32 0x7fff8000UL >>>> +#define TASK_SIZE32 (0x7fff8000UL & PAGE_SIZE) >>> >>> Same here. >> >> As above. >> >>> >>>> #define TASK_SIZE64 0x10000000000UL >>>> #define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : >>>> TASK_SIZE64) >>>> #define STACK_TOP_MAX TASK_SIZE64 >>>> >>> >> >> Thanks, >> >> Harvey >> >> > >